Balancing device for propellers



Jan. 9, 1968 J. J. FRANCIS BALANCING DEVICE FOR PROPELLERS 4 Sheets-Sheet 1 Filed Nov. 23, 1965 INVENTOR. Juan/v J F/e/z/w/a H 7704:1452 Vs yxw Jan. 9, 1968 J. J. FRANCIS. I 3,362,251

' BALANCING DEVICE FOR PROPELLERS Filed Nov. 23, 1965 4 Sheets-Sheet 2 IMQM Jan. 9, 1968 J.J.v-FRANC|S 3,362,251

BALANCING DEVICE FOR PROPELLERS I Filed Noy. 23, 1965 4 Sheets-Sheet 5 INVENTORY Jusm/ d. F QfiAlG/J 4 Sheets-Sheet 4 4..1. FRANCIS BALANCING DEVICE FOR PROPELLERS Jan. 9, 1968 Filed Nov. '25,, 1965 United States Patent Ofiice 3,362,251 Patented Jan. 9, 1968 ABSTRACT OF THE DISCLOSURE Balancing device for propellers that is adjustable for correcting hull vibration induced by a propeller shaft system. A sectionalized dunce cap provides a set of manually adjustable balancing weights.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to an adjustable device for correcting hull vibration induced by a propeller shafting system and more particularly to a sectionalized dunce cap device provided with adjustable weights and sectionalized to provide for manual underwater adjustments of the weights. I

Conventionally, correction for ship propeller shafting systems vibrations due to such causes as damage to the propeller or shaft or misalignment of bearings supporting the shaft require drydocking of the ship and balancing of the propeller and dunce cap, together with aligning of hearings or straightening of the shaft if required. Such operations are time consuming and costly and require inactivation of the ship.

. In general, the present invention comprises the provision of a manually adjustable set of balancing weights housed in a sectionalized dunce cap such that an end of the dunce cap can be removed under water while the ship is afloat and the weights adjusted manually under the same conditions. i 6

An object of the invention is to provide improved means for correcting hull vibrations due to unbalance of a propeller shafting system without drydocking the ship.

A further object is to provide a means as above which is simple and readily adjusted by a single diver.

Another object is to provide a means as indicated above which is positive in action and reliable.

A still further object is to provide a hull vibration correction device which is safe in operation for the operator and for the ship.

Other objects and advantages will appear from the following description of an example of the invention, and the novel features will be palticularly pointed out in the appended claims.

In the drawings:

FIG. 1 is a perspective view of a sectionalized dunce cap according to the invention attached to a propeller indicated and illustrating means for removing one section of the dunce cap;

FIGS. 2a and 2b are exploded views of the various elements of the dunce cap of FIG. 1 showing details of the adjusting mechanism and balancing weights;

FIG. 20 is a perspective view of the bearing plate;

FIG. 3 is a perspective view of the assembled device with part of the housing broken away to show the interior parts;

FIG. 4 is an enlarged view'in perspective showing details of the adjusting mechanism; and

FIG. 5 is a vertical elevational view partly in cross section showing details of the shafting, balance weights and adjusting mechanism.

Referring to FIGS. 1, 2a and 2b, the propeller indicated at 10 is provided with a sectionalized dunce cap 12 comprising a hollow housing 14 and a cap tip or closure 16 arranged for manual displacement of the cap tip to expose the aft end of the hollow housing 14. Any suitable closure means may be employed. In the present illustration the cap tip is threaded as at 18 in FIG. 2a and screwed into a threaded portion 20 of an aft end bearing plate 22, which is secured by welding or other suitable means to the aft end of the housing 14. The cap tip 16 is secured in tightened position by set screws 24. Both the cap tip 16 and housing 14 are formed each with a series of spaced threaded apertures 25 and 27 to receive pipe plug 26 such that spanner wrenches indicated at 28 and 30 in FIG. 1 may be employed by a diver to unscrew and remove the cap tip under water.

As best seen in FIG. 2b, the housing 14 is formed with webs 32 and studs 34 and nuts 35 or other suitable means are provided to secure the housing 14 to the hub of the propeller. The webs 32 are grooved and provided with a removable closure ring 36 to provide access to the studs 34 and nuts 35. The closure ring is secured to the webs 32 by suitable fastenings such as screws 38.

Spaced forward of the aft end bearing plate 22 is provided a forward end bearing plate 40 which is supported on a web 42 integral with the housing 14. As best seen in FIG. 5, studs 44 threaded into the web 42 and passing through apertures 46 in the forward end bearing plate are provided with nuts 47 to secure the plate 40 to the web 42. Bearing plate 40 is formed with a tubular section 48 re-inforced by fins 5t] and of internal diameter sufiicient to receive a forward bushing 52.

Journalled in the forward bushing 52 is the forward end 54 of an inner shaft 56. Shaft 56 is formed intermediate its ends with an enlarged hexagonal section 58 on which is mounted a forward eccentric weight 60 formed with a hexagonal passageway 62 therethrough to receive the hexagonal section 58 of shaft 56. A thrust bearing ring 64 is positioned on the shaft 56 between the hexagonal section 58 and the adjacent edge of forward bushing 52.

Mounted on the opposite end 64 of the inner shaft 56 are a thrust bearing ring 66 and an inner bushing 68. An outer tubular shaft 70 is mounted on the inner bushing 68 to rotate on the inner shaft 56. The outer shaft 7 0 is formed with a hexagonal sided section 72 to receive thereon an aft eccentric weight 74 having a hexagonal passageway 76 therethrough to receive the hexagonal section 72 of outer shaft 70. An outer bushing 78 is mounted on a tubular portion 80 of the outer shaft 70.

To journal the aft end of the inner shaft 56, the aft end bearing plate 22 is formed with a flange 82 (best seen in FIG. 3) which is recessed to receive the outer bushing 78.

As best seen in FIG. 5, the cylindrical portion 80 of the outer shaft is sufficiently long to pass through a central aperture 83 (see FIG. 2a) of the aft end bearing plate 22 and through a central aperture 84 (see FIG. 2a) in a circular outer shaft adjusting plate 86. To connect the adjusting plate 86 to the outer shaft 70 for adjustable rotation of the latter by rotation of the plate 86, two screw type keys 38 and (see FIG. 5) are provided. Portions of adjacent sections of the cylindrical portion 80 of outer shaft 70 and the apertured portion 84 of plate 86 are formed with threads to receive the two key screws 88 and 90 and lock the outer shaft 70 to the adjusting plate 86.

To rotatably adjust the inner shaft 56 and hence the forward Weight 74, an inner shaft adjusting plate 92 of smaller diameter than the outer shaft plate 86 is provided. The plate 92 is centrally formed with a hexagonal aperture 94 (see FIG. 2a), to mount the plate 92 3 on and mate with a hexagonal head 96 formed on the aft end of the inner shaft 56.

Thus, inner shaft 56 and its associated forward weight 60 may be adjustably rotated by rotating the inner shaft plate 92. The outer shaft 7% and its associated aft weight 74 may be adjustablyrotated by rotating the outer shaft plate 86. To lock the outer shaft plate 86 in adjusted position, diametrically positioned lugs 98 and 100 (see FIGS. 3 and 5) are provided and are respectively secured to the aft end bearing plate 22 by adjusting screws 102 and 104. To lock the inner shaft in adjusted position, diametrically opposite lugs 106 and 108 are provided and are moved by screws 111) and 112 to lock the inner shaft adjusting plate 92 to the outer shaft adjusting plate 86. As shown in FIG. 4 the inner shaft adjusting plate 92 is formed with diametrically opposed recesses 114 in the free face of the plate to receive the projecting tips of a spanner wrench indicated at 116.

Having the foregoing structure in mind, the aft and forward weights 74 and 60 may be adjusted angularly relative to each other, to provide a desired degree of weight compensation and may be adjusted in unison relative to the housing 14 to provide the necessary angularity of weight compensation required. The procedure for adjustment is as follows:

To adjust the relative angular position of weights 74 and 60, lugs 106 and 103 are loosened and adjusting plate 92 is rotated, thereby angularly adjusting forward weight 60. Lugs 98 and 100 prevent rotation of plate 86 and hence prevent rotation of aft weight 74. Thereafter lugs 106 and 108 are tightened and lugs 98 and 100 are loosened to permit rotation of both plates 92 and 86 in unison, thereby rotating weights 74 and 60 in unison. Lugs 98 and 100 are then tightened.

The degree and angularity of weight compensation required is calculated from Within the ship in conventional manner by use of conventional equipment such as a motion transducer pickup with amplifier and recorder.

Following adjustments of the weights the cap tip 16 is refastened to the dunce cap housing 14 by use of spanner wrenches such as indicated at 28 and 30 in FIG. 1.

As indicated in FIG. 2b, tapped holes 118 and 121) communicating with the interior of the dunce cap housing 14 are formed in the housing as a means for filling the housing with liquid compound silicone to avoid the effects of salt water corrosion. Plugs such as indicated at 122 are provided to seal the holes 118 and 120. The cap tip 16 is filled as indicated in FIG. 2a with a cellular polystyrene. Numerals 122 and 124 indicate respectively the ship propulsion shaft and the propeller securing nut.

An advantage of the subject invention is the ability to maintain a ship in operation without drydocking and costly time consuming operations. The operations above described can be performed underwater by a diver.

A further advantage resides in the simplicity of structure and positive displacement and locking of the adjustable weights such that accuracy of adjustment and reliability of continued fixed adjustment are inherent.

A further advantage resides in the fact that adjustments are made while the drive shafting and propeller are idle.

It will be understood that various changes in the details, materials and arrangements of parts and steps, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A balancing device for a ships propeller drive system to provide for manual underwater adjustment of tion to said propeller to rotate therewith and an open aft end to provide access to the interior of said body, a

counter balancing means housed in said body, and manually adjustable through said open aft end of said body to provide a desired degree and angularity of weight compensation to balance said propeller,

said closure means being manually displaceable to expose said manually adjustable counter-balancing means for adjustment of said counter-balancing means under water.

2. A balancing device according to claim 1,

said counter-balancing means including forward and aft spaced bearing plates, concentric inner and outer eccentric weighted shafts and means for manually ad-. justing and locking said shafts in desired angular positions in said body,

said bearing plates being mounted in said body and formed with bearing surfaces for supporting said shafts for rotation about the axis of rotation of said propeller,

said adjusting and locking means including separate manually operable members connected one to each of said shafts to adjustably rotate the same and means for manually releasably securing said members to said aft bearing plate to lock said shafts in adjustably rotated positions.

3. A balancing device according to claim 1,

said body being threaded adjacent its open aft end said closure means comprising a cap threaded to be received on the threads of said body to close the aft end thereof,

said cap and body being recessed each to receive a spanner wrench such that said cap can be manually removed under water by a diver.

4. A balancing device according to claim 2,

said body being threaded adjacent its open aft end,

said closure means comprising a cap threaded to be received on the threads of said body to close the aft end thereof,

said cap and body being recessed each to receive a spanner wrench such that said cap can be manually removed under water by a diver.

5. A balancing device according to claim 2,

said outer shaft being shorter in length than said inner shaft and tubular and mounted on said inner shaft,

said weighted shafts each comprising a shaft and an eccentric weight fixedly mounted on its associated shaft to be rotated thereby.

6. A balancing device according to claim 5,

said separate manually operable members comprising an inner shaft adjusting plate and an outer shaft adjusting plate connected respectively to said inner and outer shafts in adjacent position concentric with the common axis of rotation of said shafts,

each of said adjusting plates being recessed to accept a spanner wrench for rotatably adjusting said plates,

lug means connected to said aft bearing plate and adjustable to releasably engage and lock said outer shaft adjusting plate to said aft bearing plate, and

lug means connected to said outer shaft adjusting plate and adjustable to releasably engage and lock said inner shaft adjusting plate to said outer shaft adjusting plate.

7. A balancing device according to claim 5,

said body being threaded adjacent its open aft end,

said closure means comprising a cap threaded to be received on the threads of said body to close the aft end thereof,

said cap and body being recessed each to receive a spanner wrench such that said cap can be manually removed under water by a diver.

8. A balancing device according to claim 6,

said body being threaded adjacent its open aft end,

said closure means comprising a cap threaded to be received on the threads of said body to close the aft end thereof,

said cap and body being recessed each to receive a spanner wrench such that said cap can be manually 5 removed under water by a diver.

9. A balancing device according to claim 6,

said inner shaft being formed with a multisided end and said inner shaft adjusting plate being formed with a multisided central aperture to mate with said 10 end,

References Cited UNITED STATES PATENTS 2,722,848 11/1955 Stein 170-159 X MILTON KAUFMAN, Primary Examiner. 

